An evaporator provided in a refrigeration unit can decrease ambient temperature using cool air generated by the circulation of coolant flowing through a cooling tube. During the cooling process, due to temperature difference with ambient air, moisture in the air may condense and freeze on a surface of the cooling tube. In some cases, an electric heater may be used to remove such frost formed on the evaporator.
In recent years, a defrosting device using a heat pipe has been developed and contrived, and the related technologies include Korean Patent Registration No. 10-0469322, entitled “Evaporator,” Korean Patent Registration No. 10-1036685, entitled “Loop-shaped heat pipe using bubble jet,” and Korean Patent Registration No. 10-1125827, entitled “Defrosting module to which loop-shaped heat pipe using bubble jet is applied.”
However, the foregoing heat pipe type defrosting device has the following drawbacks.
According to a heat pipe type defrosting device in the related art, working fluid within an evaporating unit is filled only in a lower portion of the evaporating unit while the evaporating unit (or heating unit) is vertically or horizontally disposed, and thus the amount thereof is very small in a defrosting device applied to typical household refrigerators.
The use of small amount of working fluid can increase an evaporation rate due to rapid heating, but has a danger of overheating an electric heater provided in the evaporating unit when it is applied to a household refrigerator.
According to a heat pipe type defrosting device in the related art, both end portions of the condensing unit is configured at one side (or an upper portion) of the evaporating unit, and working fluid is filled and heated only in the other side (a lower portion) of the evaporating unit to generate high bubble propulsion. Therefore, it is possible to obtain flow such as vibration circulation within a heat pipe, but causes a problem of preventing the flow of vapor within the heat pipe from being circulated in one direction.
Though a heat pipe type defrosting device in the related art obtains high bubble propulsion, there is a problem in that efficient circulation flow is suppressed within the heat pipe.
Typically, a heat pipe type defrosting device may largely include an evaporating unit configured to heat liquid refrigerant, and a condensing unit having an entrance portion connected to one side of the evaporating unit to receive working fluid (including working fluid in the vapor phase heated at high temperatures or working fluid in the liquid phase at high temperatures) and a return portion connected to the other side of the evaporating unit to return working fluid again to the evaporating unit.
Here, in a structure in which working fluid is immediately collected to the side of an electric heater at high temperatures installed on an inner side of the evaporating unit or bubbles at temperatures generated by the heating of the electric heater returns to the location of propulsion, there may occur a case where the collected working fluid is reheated to flow back without being efficiently returned into the evaporating unit. It may cause a problem in that the circulation flow of working fluid within the heat pipe is suppressed to overheat the entire evaporating unit or heat pipe.
In such a structure in which the circulation flow of working fluid within the heat pipe is suppressed or a case where working fluid is collected again to the evaporating unit by the gravity of working fluid along an inner surface of the heat pipe constituting the condensing unit, when the condensing unit has a horizontal section, working fluid may remain without being efficiently circulated, thereby causing a problem in that the collection of working fluid is not effectively carried out.
In case where a heat pipe type defrosting device has a circulation structure using the vibration of working fluid, there is a problem in that it takes long time until the entire section of the heat pipe reaches a stable working temperature.